Personal Research Database

Full Text: 2006\J Haz Mat131, 137.pdf

Abstract: The study was aimed of determining the Zn(II) sorption performance of Botrytis cinerea (B. cinerea) biomass as a new biosorbent. Heat inactivated biomass was used in the determination of optimum conditions. The rate and extent of accumulation were effected by pH, contact time and initial zinc ion concentrations. The uptake capacity of B. cinerea was increased by chemical and physical pretreatment of the cells when compared with the native biomass. The maximum removal of Zn(II) at pH 5.0–6.0 was found to be 12.98±0.9623 mg g⁻¹ at initial Zn(II) ion concentration of 100 mg l⁻¹ by heat inactivated biomass. Freundlich and Langmuir isotherm models were used to evaluate the data and regression constants were derived. The biosorbent was regenerated using 10 mM HCl solution, with up to 98% recovery and reused five times in biosorption–desorption cycles successivelly. Competitive biosorption experiments were performed with zinc in the presence of copper, cadmium and nickel ions simultaneously. The nature of the possible cell–metal ions interactions was also evaluated by chemical and instrumental analysis including infrared spectroscopy, scanning electron microscopy and X-ray energy dispersion analysis.

Keywords: Botrytis Cinerea, Biosorption, Zinc(II), Freundlich Isotherm, Langmuir Isotherm, Desorption

? Rivas, F.J., Beltrán, F.J., Gimeno, O., Frades, J. and Carvalho, F. (2006), Adsorption of landfill leachates onto activated carbon: Equilibrium and kinetics. Journal of Hazardous Materials, 131 (1-3), 170-178.

Full Text: 2006\J Haz Mat131, 170.pdf

Abstract: The adsorption of stabilized leachates generated in a municipal landfill onto three commercial activated carbons has been investigated. Norit 0.8, Chemviron AQ40 and Picacarb 1240 have been used as adsorbents. Equilibrium experiments have been conducted to obtain the experimental isotherm profiles. Isotherms have been plotted based on the adsorption of general parameters, for instance chemical oxygen demand, total carbon, absorption at 410 nm and absorption at 254 nm. Different literature models and error functions have been used to adequately fit the experimental data. As a rule of thumb, three-parameter models do adjust experimental results better than two-parameter models. Norit 0.8 shows better adsorption characteristics than the rest of activated carbons, both in terms of contaminant level reduction of per unit mass of absorbent and in terms of the process kinetics.

Keywords: Landfilling, Leachates, Adsorption, Activated Carbon, Isotherm, Kinetics

? Shashidhar, T., Philip, L. and Bhallamudi, S.M. (2006), Bench-scale column experiments to study the containment of Cr(VI) in confined aquifers by bio-transformation. Journal of Hazardous Materials, 131 (1-3), 200-209.

Full Text: 2006\J Haz Mat131, 200.pdf

Abstract: Bench-scale soil column experiments were conducted to study the effectiveness of Cr(VI) containment in confined aquifers using in situ bio-transformation. Batch adsorption studies were carried out to estimate the adsorption capacities of two different soils for Cr(VI) and Cr(III). Bio-kinetic parameters were evaluated for the enriched microbial system. The inhibition constant, evaluated using Monod’s inhibition model, was found to be 11.46 mg/L of Cr(VI). Transport studies indicated that it would not be possible to contain Cr(VI) by adsorption alone. Transport and bio-transformation studies indicated that the pore velocity and the initial bio-mass concentration significantly affect the containment process. In situ bio-remediation is effective in the case of silty aquifers. Cr(VI) concentration of 25 mg/L was effectively contained within 60 cm of a confined silty aquifer. Cr(VI) containment could be achieved in sandy aquifers when the pore velocity was very low and the initial augmented bio-mass was high. A bio-barrier of approximately one meter width would be able to contain Cr(VI) if the initial Cr(VI) concentration is as much as 25 mg/L.

Keywords: Bio-Transformation, Chromium, Contaminant Transport, Column Experiments

? Gürses, A., Doğar, Ç., Yalçın, M., Açıkyıldız, M., Bayrak, R. and Karaca, S. (2006), The adsorption kinetics of the cationic dye, Methylene Blue, onto clay. Journal of Hazardous Materials, 131 (1-3), 217-228.

Full Text: 2006\J Haz Mat131, 217.pdf

Abstract: In this study, adsorption kinetics of a cationic dye, methylene blue, onto clay from aqueous solution with respect to the initial dye concentration, temperature, pH, mixing rate and sorbent dosage were investigated. In order to understand the adsorption mechanism in detail, zeta potentials and the conductivities of clay suspensions at various pH (1–11) and cation exchange capacity (CEC) were measured. Porosity and BET surface area of clay studied were determined. The results showed that the adsorption has been reached to equilibrium in 1 h. It was found that the amount adsorbed of methylene blue increases with decreasing temperature and also with increasing both sorbent dosage and increasing initial dye concentration. Adsorption capacity decreases with increasing pH, except for the natural pH (5.6) of clay suspensions. The adsorption kinetics of methylene blue has been studied in terms of pseudo-first-order, pseudo-second-order sorption and intraparticle diffusion processes thus comparing chemical sorption and diffusion sorption processes. It was found that the pseudo-second-order mechanism is predominant and the overall rate of the dye adsorption process appears to be controlled by the more than one-step.

Keywords: Adsorption, Adsorption Capacity, Adsorption Kinetics, Adsorption Mechanism, Aqueous Solution, BET, BET Surface Area, Capacity, Cation, Cation Exchange, Cationic Dye, Chemical, Clay, Concentration, Diffusion, Diffusion Processes, Dye, Dye Adsorption, Equilibrium, Intraparticle Diffusion, Kinetics, Mechanism, Methylene Blue, Mixing, pH, Pseudo First Order, Pseudo Second Order, Pseudo-First-Order, Pseudo-First-Order Kinetics, Pseudo-Second-Order, Pseudo-Second-Order Kinetics, Solution, Sorbent, Sorption, Surface, Surface Area, Temperature

? Cañizares, P., Carmona, M., Baraza, O., Delgado, A. and Rodrigo, M.A. (2006), Adsorption equilibrium of phenol onto chemically modified activated carbon F400. Journal of Hazardous Materials, 131 (1-3), 243-248.

Full Text: 2006\J Haz Mat131, 243.pdf

Abstract: In this work the adsorption of phenol solutions onto activated carbon Calgon F400 has been studied. The carbon was modified by acid treatment, using soxhlet extraction with hydrochloric acid 2N for 120 cycles. The treatment did not affect significantly the surface area of the activated carbon but affected significatively the different functional groups, and thus its adsorption properties. Tóth model reproduced satisfactorily the experimental isotherm data and an adsorption enthalpy of −17.9 kJ mol⁻¹ was found, which indicates that the process is exothermic. The pH affected significatively to the adsorption process and an empirical polynomial equation was able to reproduce maximum capacity as a function of pH. The isotherms obtained at pH 3 and 7 are very similar and showed a higher adsorption capacity compared with that obtained at pH 13. The use of phosphate buffer solutions decreased the maximum phenol adsorption capacity, due to the competitive adsorption between the phenol and phosphates. Finally, it was demonstrated that the acid treatment introduced chloride ions into the carbon, giving it properties of ion exchanger.

Keywords: Acid Treatment, Acid-Treatment, Activated Carbon, Adsorption, Adsorption Properties, Aqueous Phenol, Buffer, Capacity, Carbon, Chloride, Desorption, Equilibrium, Extraction, Functional Groups, Heterogeneity, Hydrochloric Acid, Ion, Ion Exchange, Ion-Exchange, Isotherm, Isotherms, Langmuir, Mechanisms, Model, Modified, pH, Phenol, Phenolate, Phosphate, Properties, Regeneration, Removal, Surface, Surface Area, Surface-Properties, Toth, Treatment, Wastes, Water

? Gürses, A., Doğar, Ç., Karaca, S., Açikyildiz, M. and Bayrak, R. (2006), Production of granular activated carbon from waste Rosa canina sp. seeds and its adsorption characteristics for dye. Journal of Hazardous Materials, 131 (1-3), 254-259.

Full Text: 2006\J Haz Mat131, 254.pdf

Abstract: An activated carbon was developed from Rosa canina sp. seeds, characterized and used for the removal of methylene blue (basic dye) from aqueous solutions. Adsorption studies were carried out at 20 °C and various initial dye concentrations (20, 40, 60, 80, and 100 mg/L) for different times (15, 30, 60, and 120 min). The adsorption isotherm was obtained from data. The results indicate that the adsorption isotherm of methylene blue is typically S-shaped. The shape of isotherm is believed to reflect three distinct modes of adsorption. In region 1, the adsorption of methylene blue is carried out mainly by ion exchange. In region 2 by polarizations of π-electrons established at cyclic parts of the previously adsorbed methylene blue molecules is occurred. However, it is not observed any change at the sign of the surface charge although zeta potential value is decreased with increase of amount adsorbed. In region 3, the slope of the isotherm is reduced, because adsorption now must overcome electrostatic repulsion between oncoming ions and the similarly charged solid. Adsorption in this fashion is usually complete when the surface is covered with a monolayer of methylene blue. To reveal the adsorptive characteristics of the produced active carbon, porosity and BET surface area measurements were made. Structural analysis was performed using SEM–EDS. The produced active carbon has the specific surface area of 799.2 m² g⁻¹ and the iodine number of 495 mg/g.

Keywords: Rosa Canina, Iodine Number, Adsorption Isotherm, Chemical Activation, Active Carbon

? Benaïssa, H. (2006), Screening of new sorbent materials for cadmium removal from aqueous solutions. Journal of Hazardous Materials, 132 (2-3), 189-195.

Full Text: 2006\J Haz Mat132, 189.pdf

Abstract: This study compares the abilities of four low-cost materials: peels of peas, broad bean, and medlar, respectively and fig leaves, to remove cadmium from aqueous solutions. Kinetic data and equilibrium sorption isotherms were measured in batch conditions. Kinetics of cadmium sorption was contact time, initial cadmium concentration and sorbent type dependent. The results also showed that the kinetics of cadmium sorption were described by a pseudo second-order rate model. The cadmium uptake of these low-cost materials was quantitatively evaluated using sorption isotherms. Results indicated that Langmuir model gave an acceptable fit to the experimental data. A high cadmium sorption was observed by these materials. The broad bean peel was the most effective to remove cadmium ions with a maximum sorption capacity about 147.71 mg/g followed by peas peel (118.91 mg/g), fig leaves (103.09 mg/g), and medlar peel (98.14 mg/g).

Keywords: Aqueous Solutions, Batch, Broad Bean Peel, Cadmium, Cadmium Ions, Capacity, Concentration, Data, Equilibrium, Experimental, Isotherms, Kinetic, Kinetics, Langmuir, Langmuir Model, Low-Cost Materials, Model, Pseudo Second Order, Pseudo Second-Order, Pseudo-Second-Order, Removal, Screening, Second Order, Second-Order, Solutions, Sorbent, Sorption, Sorption Capacity, Sorption Isotherms, Uptake

? Noubactep, C., Schöner, A. and Meinrath, G. (2006), Mechanism of uranium removal from the aqueous solution by elemental iron. Journal of Hazardous Materials, 132 (2-3), 202-212.

Full Text: 2006\J Haz Mat132, 202.pdf

Abstract: The effectiveness of elemental iron (Fe⁰) to remove uranium(U) from the aqueous phase has been demonstrated. While the mitigation effect is sure, discrepancies in the removal mechanism have been reported. The objective of this study was to investigate the mechanism of U(VI) removal from aqueous phases by Fe⁰. For this purpose, a systematic sequence of bulk experiments was conducted to characterize the effects of the availability and the abundance of corrosion products on U(VI) removal. Results indicated that U(VI) removal reactions did not primary occur at the surface of the metallic iron. It is determined that U(VI) co-precipitation with aging corrosion products is a plausible explanation for the irreversible fixation under experimental conditions. Results of XRD analyses did no show any U phases, whereas SEM-EDX analyses showed that U tended to associate with rusted areas on the surface of Fe⁰. Recovering U with different leaching solutions varied upon the dissolution capacity of the individual solutions for corrosion products, showing that the irreversibility of the removal depends on the stability of the corrosion products. U(VI) co-precipitation as removal mechanism enables a better discussion of reported discrepancies.

Keywords: Abundance, Adsorption, Aging, Aqueous Phase, Aqueous Solution, Capacity, Co-Precipitation, Contaminated Aquifer, Corrosion, Dissolution, Effectiveness, Effects, Elemental Iron, Groundwater, Immobilization, Iron, Leaching, Mechanism, Permeable Reactive Barriers, Products, Reducing Conditions, Reduction, Removal, Removal Mechanism, SEM-EDX, Stability, Steel Surfaces, Surface, Titanium, U(VI), Uranium, XRD, Zero-Valent Iron, Zerovalent Iron

? Quesnel, D. and Nakhla, G. (2006), Removal kinetics of acetone and MIBK from a complex industrial wastewater by an acclimatized activated sludge. Journal of Hazardous Materials, 132 (2-3), 253-260.

Full Text: 2006\J Haz Mat132, 253.pdf

Abstract: Removal rates of acetone and methyl isobutyl ketone (MIBK) were determined singularly and in combination in batch experiments employing an acclimatized activated sludge from a pilot system treating an organic chemical manufacturer industrial wastewater, as well as during the course of operation of the pilot system. Both acetone and MIBK removals were described by first-order removal kinetics. Acetone, as a single substrate, was biodegraded at a rate of 1.7 day⁻¹. MIBK was biodegraded, during the single-substrate experiments, at an observed rate of 2.23 day⁻¹. Relative to the control (no spike) experiments, acetone removal was augmented by a factor of 3 during the acetone spike, with an observed biomass-specific removal rate of 0.0023 L/mg VSS day. MIBK removal during an MIBK spike was also enhanced by a factor of 2, and the greatest biomass-specific removal rate of MIBK was observed during the acetone spike of 0.0019 L/mg VSS day. The observed rates were approximately 3 orders of magnitude greater than the observed rates in the pilot scale system. MIBK exerted a synergistic effect on the acetone-removal rate while acetone exerted an inhibitory impact on the MIBK-removal rate.

Keywords: Industrial Wastewater, Acetone, MIBK, Activated Sludge, Biodegradation Kinetics, Extant, Intrinsic

? Vázquez, G., Alonso, R., Freire, S., González-Álvarez, J. and Antorrena, G. (2006), Uptake of phenol from aqueous solutions by adsorption in a Pinus pinaster bark packed bed. Journal of Hazardous Materials, 133 (1-3), 61-67.

Full Text: 2006\J Haz Mat133, 61.pdf

Abstract: The adsorption of phenol from aqueous solutions using a column packed with pre-treated Pinus pinaster bark was studied. The influence of the inlet phenol concentration (0.01 or 0.1 g/L) and the flow rate (6, 15.6 or 30 mL/min) on the breakthrough curves was analysed. An increase in the flow rate, decreased the time necessary to reach the breakthrough point and, for the highest inlet concentration, the dynamic capacity of the bed, from 7.5 to 0.4 min and from 0.38 to 0.15 mg phenol/g o.d. bark, respectively, at 0.1 g/L. The LUB Design Approach was used to determine the equivalent length of unused bed. The lower LUB values, which imply a better utilization of the bark bed, were obtained at the higher flow rate. A model which considered the effect of axial dispersion was successfully used to describe the fixed-bed operation behaviour for the lower flow rates. For the lowest inlet phenol concentration, the axial dispersion coefficient increased significantly when the flow rate increased.

Keywords: Adsorption, Pinus Pinaster Bark, Fixed-Bed Column, Breakthrough Curves, Modelling

? Contreras, C., de la Rosa, G., Peralta-Videa, J.R. and Gardea-Torresdey, J.L. (2006), Lead adsorption by silica-immobilized humin under flow and batch conditions: Assessment of flow rate and calcium and magnesium interference. Journal of Hazardous Materials, 133 (1-3), 79-84.

Full Text: 2006\J Haz Mat133, 79.pdf

Abstract: Batch and column experiments were performed to determine the Pb(II) binding ability of silica-immobilized humin biomass under different conditions. Batch experiments were performed to determine the interference of Ca(II) and Mg(II) and column experiments were used to determine the effect of flow rate and the presence of Ca(II) and Mg(II) on the Pb(II) adsorption by the humin biopolymer. The results from the batch experiments showed that Pb binding decreased as the concentrations of Ca and Mg increased. At a concentration of 100 mM, the interference of Ca alone was 36%, while for Mg it was 26%; however, when both cations were present, the interference increased up to 42%. Column experiments were performed at flow rates of 1, 1.5, 2, and 3 mL min⁻¹ using a 0.1 mM Pb(II) solution. The results showed that the highest Pb adsorption was obtained at the flow rates of 1 and 1.5 mL min⁻¹. The average Pb binding capacity at these two flow rates was 182.3±0.7 μM Pb g⁻¹. In addition, a recovery of 99.5±0.3% was obtained. Immobilized humin exposed under flow conditions to Pb–Ca, Pb–Mg or Pb–[Ca+Mg] solutions (Pb used at 0.1 mM and Ca and Mg at 1 mM) showed a Pb binding capacity of 161±5, 175±5, and 171±1 μM g⁻¹, respectively. In mixtures containing Pb–Ca, Pb–Mg and Pb–Ca–Mg, the Pb recovery was 89.8%±0.35, 90.3%±0.43, and 88.1%±0.5, respectively. Pb recovery was performed using 30 bed volumes of 0.1 M HCl as stripping agent. The results of these experiments demonstrated that silica-immobilized humin biomass has the potential for Pb removal from aqueous solution even in the presence of 20 mM of calcium and magnesium.

Keywords: Humin-Polymer, Lead, Column, Adsorption, Hard Cations

? Wang, G., Wu, F., Zhang, X., Luo, M. and Deng, N. (2006), Enhanced TiO₂ photocatalytic degradation of bisphenol E by -cyclodextrin in suspended solutions. Journal of Hazardous Materials, 133 (1-3), 85-91.

Full Text: 2006\J Haz Mat133, 85.pdf

Abstract: Enhancement of beta-cyclodextrin (beta-CD) on TiO2 Photocatalytic degradation of bisphenol E (BPE, bis(4-hydroxyphenyl)ethane) was investigated under a 250 W metal halide lamp ( lambda >= 365 nm) in this work. In the system of photocatalytic degradation of BPE, the photodegradation rate of BPE in aqueous solutions containing beta-CD and TiO2 was obviously faster than that in aqueous solutions containing only Tio(2). After 40 min of irradiation, beta-CD could increase the photodegradation efficiency by about 26% for 10 mg l(-1) BPE in the UV-vis/TiO2 system and the photodegradation of 2.5-20.0 mg l(-1) BPE in aqueous solutions was found to follow pseudo-first-order law and the adsorption constant and the reaction rate constant of BPE in the system containing beta-CD and TiO2 are obviously higher than those in the system containing only TiO2, the influence factors on photode.-radation of BPE were studied and described in details, such as beta-CD concentration, pH, BPE initial concentration and gas medium. The formation of CO2 as a result of mineralization of BPE was observed during the photodegradation process. After 120 min of irradiation, the mineralization efficiency of BPE reached 61% in the presence of beta-CD, whereas mineralization efficiency was only 23% in the absence of beta-CD. The enhancement of photodegradation of BPE could be dependent on the enhancement of adsorption of BPE on TiO2 surface and moderate inclusion-depth of BPE in the beta-CD cavity. (c) 2005 Elsevier B.V. All rights reserved.

Keywords: Adsorption, Assemblies, Beta-Cyclodextrin, Bisphenol E, CO₂, Colloids, Degradation, Electron-Transfer Processes, Enhancement, Metal, pH, Photocatalytic, Photocatalytic Degradation, Photodegradation, Pseudo-First-Order, Rate Constant, Semiconductor Photocatalysis, Water

? Lv, L., He, J., Wei, M., Evans, D.G. and Duan, X. (2006), Factors influencing the removal of fluoride from aqueous solution by calcined Mg-Al-CO₃ layered double hydroxides. Journal of Hazardous Materials, 133 (1-3), 119-128.

Full Text: 2006\J Haz Mat133, 119.pdf

Abstract: Layered double hydroxides (LDH) calcined at different temperatures (denoted as CLDH) have been demonstrated to recover their original layered structure in the presence of appropriate anions. In the light of this so-called “memory effect”, a study of removal of fluoride from aqueous solution by calcined Mg-Al-CO³-LDH has been carried out. The LDH calcined at 500C had the highest capacity of removal of fluoride ion, because of retention of its intrinsic structure. The CLDH with an Mg/Al ratio of 2 has a remarkable ability to adsorb anions. The adsorption loading is higher for the calcined Mg-Al-LDH than for calcined Zn-Al and Ni-Al-LDH. The influence of varying the conditions for removal of fluoride, such as the pH of aqueous solution, the initial fluoride concentration, the dosage of adsorbent, and temperature on removal of fluoride have been investigated. The influence of co-existing anions in fluoride aqueous solution indicates that the percentage of removal of fluoride increased in order PO₄^3- < Cl^- approximate to SO₄^2- < Br^- << NO₃^-. It was found that maximum removal of fluoride from aqueous solutions was obtained in 6h at pH 6.0 with an initial concentration of 50 mg/L, and that the retention of fluoride ions by the CLDH material was 98% or higher. The residual fluoride concentration was found to be 0.4 mg/L with an initial concentration of 20 mg/L, which meets the national standard for drinking water quality. The Freundlich isotherm and Langmuir isotherm were used to fit the data of equilibrium experiments. The results of X-ray diffraction, FT-IR and TG-MS demonstrate that the adsorption phenomenon is accompanied by rehydration with concomitant uptake of fluoride ions to rebuild the initial layered structure. (c) 2005 Elsevier B.V. All rights reserved.

Keywords: Layered Double Hydroxides, Adsorption, Removal, Fluoride, Memory Effect, Calcined, Hydrotalcite-Like Compounds, Adsorption Behavior, Water, Defluoridation, Kinetics, Sorption, Equilibrium, Sorbents, Sludge

? Brasil, J.L., Ev, R.R., Milcharek, C.D., Martins, L.C., Pavan, F.A., dos Santos, Jr., A.A., Dias, S.L.P., Dupont, J., Zapata Noreña, C.P. and Lima, E.C. (2006), Statistical design of experiments as a tool for optimizing the batch conditions to Cr(VI) biosorption on Araucaria angustifolia wastes. Journal of Hazardous Materials, 133 (1-3), 143-153.

Full Text: 2006\J Haz Mat133, 143.pdf

Abstract: In order to reduce the total number of experiments for achieving the best conditions for Cr(VI) uptake using Araucaria angustifolia (named pinhão) wastes as a biosorbent, three statistical design of experiments were carried out. A full 2⁴ factorial design with two blocks and two central points (20 experiments) was experimented (pH, initial metallic ion concentration—C_o, biosorbent concentration—X and time of contact—t), showing that all the factors were significant; besides, several interactions among the factors were also significant. These results led to the performance of a Box–Behnken surface analysis design with three factors (X, C_o and t) and three central points and just one block (15 experiments). The performance of these two statistical designs of experiments led to the best conditions for Cr(VI) biosorption on the pinhão wastes using a batch system, where: pH 2.0; C_o = 1200 mg l⁻¹ Cr(VI); X = 1.5 g l⁻¹ of biosorbent; t = 8 h. The maximum Cr(VI) uptake in these conditions was 125 mg g⁻¹. After evaluating the best Cr(VI) biosorption conditions on pinhão wastes, a new Box–Behnken surface analysis design was employed in order to verify the effects of three concomitant ions (Cl⁻, NO₃⁻ and PO₄³⁻) on the biosorption of Cr(VI) as a dichromate on the biosorbent (15 experiments). These results showed that the tested anions did not show any significant effect on the Cr(VI) uptake by pinhão wastes. In order to evaluate the pinhão wastes as a biosorbent in dynamic system, a glass column was fulfilled with pinhão wastes (4.00 g) as biosorbent, and it was fed with 25.0 mg l⁻¹ Cr(VI) at pH 2.0 and 2.5 ml min⁻¹. The breakpoint was attained when concentrations of effluent of the column attained the value of 0.05 mg l⁻¹ Cr(VI) using 5550 ml of the metallic ion solution. In these conditions, the biosorbent was able to remove completely Cr(VI) from aqueous solution with a ratio of Cr(VI) effluent volume/biosorbent volume of 252.3.

Keywords: Aracauria Angustifolia Wastes, Biosorption, Chromium(VI), Factorial Design, Box–Behnken Surface Analysis

? Bouberka, Z., Khenifi, A., Benderdouche, N. and Derriche, Z. (2006), Removal of Supranol Yellow 4GL by adsorption onto Cr-intercalated montmorillonite. Journal of Hazardous Materials,